Election: Gay marriage turns into key battleground as DUP and Alliance clash
The Alliance Party has been accused of "total hypocrisy" over 'opt-outs' for churches and businesses in legislation.
The DUP argued Alliance wants protections for Christian ministers which it is denying to Christian business people.
But Alliance insisted the DUP was "match and mixing" two completely separate issues and had simply "got it wrong".
With the two parties slugging it out - particularly over the cockpit contest of East Belfast which Alliance's Naomi Long seized from DUP leader Peter Robinson in 2010 - their contrasting approach to same-sex rights is one main area of contention.
Alliance's manifesto for next week's election supports the extension of civil marriage provisions to same-sex couples "provided that robust protections are provided through legislation to protect faith groups and religious celebrants who do not wish to marry same-sex couples".
But at the same time the party is opposed to the DUP's proposed 'conscience clause' which arises from the Ashers bakery controversy.
The DUP's East Antrim candidate Sammy Wilson said: "It is not only totally hypocritical of the Alliance Party, it is dishonest. It is hypocritical because they are seeking protections for one set of Christians but denying them for another.
"And it is dishonest because regardless of what is put into legislation, they know that over time the law is eroded by cases it cannot cover.
"Why should Christian ministers enjoy an opt-out which is denied to Christian businessmen? I don't know why they have taken such a position, it may be just to provide shallow cover for their policies."
But Alliance East Antrim standard-bearer Stewart Dickson said: "Yet again the DUP has got it wrong, they are mixing and matching two completely separate issues.
"On the one hand marriage is a sacrament while what businesses do is to provide a service. The reason why ministers of religion need protections is because they are licensed to act on behalf of the state as registrars.
"But once you set up a business you cannot really separate out your business from those who you wish to do business with. Conscience clauses, whereby someone can refuse to employ someone or provide a service due to potential conflict with their stated beliefs, can only be considered in very specific and defined circumstances where an exceptional case can be made."
The Alliance manifesto also says the DUP's 'conscience clause' is poorly defined and could become a "charter for discrimination". But it backs lifting the bans on gay and unmarried couples adopting and the lifetime ban on gay men giving blood, which would bring Northern Ireland into line with the rest of the UK.
A verdict on the Ashers bakery case, in which a Christian firm refused to make a cake with a pro-gay marriage slogan, is expected next Thursday.
The Equality Commission brought the case against the family-run Newtownabbey firm on behalf of a gay rights activist whose order for a cake with the image of Sesame Street characters Ernie and Bert with the slogan 'support gay marriage' was declined. The cake was being ordered for an event which was due to be hosted by then Alliance North Down Mayor Andrew Muir. Another bakery in Bangor stepped in and produced the cake for the event for International Day Against Homophobia and Transphobia.